*The content is good. However, I think it is a pity to pay for it. It would be better if it was free or less than 3,000 won. I saw that the instructor has a follow-up lecture. I think it would be appropriate for people who are satisfied with this lecture to take the follow-up lecture and pay for it. *When I read other people's posts, they said that the explanation is fast, but it is not simply that it is difficult to understand because the explanation is fast, but I think it is lacking in the technique of matching the chart and the explanation or the explanation using cases or examples. In fact, I feel stressed the whole time I listen. I have to stop and say, "What is this?"... *I listened to this lecture while reading the Insight Java book... The topics are similar. However, the nature of this lecture is ambiguous. It does not cover a wider area than Insight Java, and it does not help you understand the core concepts that were difficult to understand with Insight Java alone... When I paid for this lecture, I expected it to be just a supplementary lecture to help you understand Insight well, but I think it fell short in that role. I should have thought that it was a waste of money and time to grasp this one concept.